Comparative evaluation of the model-centred and the application-centred design approach in civil engineering software

[摘要] ENGLISH ABSTRACT:In this dissertation the traditional model-centred (MC)design approach forthe development of software in the civil engineering field is compared to anewly developed application-centred (AC)design approach.In the MC design software models play the central role. A software modelmaps part of the world, for example its visualization or analysis onto thememory space of the computer. Characteristic of the MC design is that theidentifiers of objects are unique and persistent only within the name scopeof a model, and that classes which define the objects are components of themodel.In the AC design all objects of the engineering task are collected in an application.The identifiers of the objects are unique and persistent within the namescope of the application and classes are no longer components of a model,but components of the software platform. This means that an object can be apart of several models.It is investigated whether the demands on the information and communicationin modern civil engineering processes can be satisfied using the MCdesign approach. The investigation is based on the evaluation of existing softwarefor the analysis and design of a sewer reticulation system of realisticdimensions and complexity. Structural, quantitative, as well as engineeringcomplexity criteria are used to evaluate the design. For the evaluation of thequantitative criteria, in addition to the actual Duration of Execution, a User InteractionCount, the Persistent Data Size, and a Basic Instruction Count basedon a source code complexity analysis, are introduced.The analysis of the MCdesign shows that the solution of an engineering taskrequires several models. The interaction between the models proves to becomplicated and inflexible due to the limitation of object identifier scope: Theengineer is restricted to the concepts of the software developer, who mustprovide static bridges between models in the form of data files or softwaretransformers.The concept of the ACdesign approach is then presented and implemented ina new software application written in Java. This application is also extendedfor the distributed computing scenario. Newbasic classes are defined to managethe static and dynamic behaviour of objects, and to ensure the consistentand persistent state of objects in the application. The same structural andquantitative analyses are performed using the same test data sets as for theMCapplication.It is shown that the AC design approach is superior to the MC design approachwith respect to structural, quantitative and engineering complexity.criteria. With respect to the design structure the limitation of object identifierscope, and thus the requirement for bridges between models, falls away,which is in particular of value for the distributed computing scenario. Althoughthe new object management routines introduce an overhead in theduration of execution for the AC design compared to a hypothetical MC designwith only one model and no software bridges, the advantages of the designstructure outweigh this potential disadvantage.

[发布机构] Stellenbosch University